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/*
 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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package java.time.chrono;

import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.DAY_OF_YEAR;
import static java.time.temporal.ChronoField.ERA;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoField.YEAR;
import static java.time.temporal.ChronoField.YEAR_OF_ERA;
import static java.time.temporal.ChronoUnit.DAYS;
import static java.time.temporal.ChronoUnit.MONTHS;

import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.Clock;
import java.time.DateTimeException;
import java.time.Instant;
import java.time.LocalDate;
import java.time.Year;
import java.time.ZoneId;
import java.time.format.ResolverStyle;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjusters;
import java.time.temporal.TemporalField;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Arrays;
import java.util.Calendar;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import sun.util.calendar.CalendarSystem;
import sun.util.calendar.LocalGregorianCalendar;

/**
 * The Japanese Imperial calendar system.
 * <p>
 * This chronology defines the rules of the Japanese Imperial calendar system.
 * This calendar system is primarily used in Japan.
 * The Japanese Imperial calendar system is the same as the ISO calendar system
 * apart from the era-based year numbering.
 * <p>
 * Japan introduced the Gregorian calendar starting with Meiji 6.
 * Only Meiji and later eras are supported;
 * dates before Meiji 6, January 1 are not supported.
 * <p>
 * The supported {@code ChronoField} instances are:
 * <ul>
 * <li>{@code DAY_OF_WEEK}
 * <li>{@code DAY_OF_MONTH}
 * <li>{@code DAY_OF_YEAR}
 * <li>{@code EPOCH_DAY}
 * <li>{@code MONTH_OF_YEAR}
 * <li>{@code PROLEPTIC_MONTH}
 * <li>{@code YEAR_OF_ERA}
 * <li>{@code YEAR}
 * <li>{@code ERA}
 * </ul>
 *
 * @implSpec This class is immutable and thread-safe.
 * @since 1.8
 */
public final class JapaneseChronology extends AbstractChronology implements Serializable {

  static final LocalGregorianCalendar JCAL =
      (LocalGregorianCalendar) CalendarSystem.forName("japanese");

  // Locale for creating a JapaneseImpericalCalendar.
  static final Locale LOCALE = Locale.forLanguageTag("ja-JP-u-ca-japanese");

  /**
   * Singleton instance for Japanese chronology.
   */
  public static final JapaneseChronology INSTANCE = new JapaneseChronology();

  /**
   * Serialization version.
   */
  private static final long serialVersionUID = 459996390165777884L;

  //-----------------------------------------------------------------------

  /**
   * Restricted constructor.
   */
  private JapaneseChronology() {
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the ID of the chronology - 'Japanese'.
   * <p>
   * The ID uniquely identifies the {@code Chronology}.
   * It can be used to lookup the {@code Chronology} using {@link Chronology#of(String)}.
   *
   * @return the chronology ID - 'Japanese'
   * @see #getCalendarType()
   */
  @Override
  public String getId() {
    return "Japanese";
  }

  /**
   * Gets the calendar type of the underlying calendar system - 'japanese'.
   * <p>
   * The calendar type is an identifier defined by the
   * <em>Unicode Locale Data Markup Language (LDML)</em> specification.
   * It can be used to lookup the {@code Chronology} using {@link Chronology#of(String)}.
   * It can also be used as part of a locale, accessible via
   * {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
   *
   * @return the calendar system type - 'japanese'
   * @see #getId()
   */
  @Override
  public String getCalendarType() {
    return "japanese";
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains a local date in Japanese calendar system from the
   * era, year-of-era, month-of-year and day-of-month fields.
   * <p>
   * The Japanese month and day-of-month are the same as those in the
   * ISO calendar system. They are not reset when the era changes.
   * For example:
   * <pre>
   *  6th Jan Showa 64 = ISO 1989-01-06
   *  7th Jan Showa 64 = ISO 1989-01-07
   *  8th Jan Heisei 1 = ISO 1989-01-08
   *  9th Jan Heisei 1 = ISO 1989-01-09
   * </pre>
   *
   * @param era the Japanese era, not null
   * @param yearOfEra the year-of-era
   * @param month the month-of-year
   * @param dayOfMonth the day-of-month
   * @return the Japanese local date, not null
   * @throws DateTimeException if unable to create the date
   * @throws ClassCastException if the {@code era} is not a {@code JapaneseEra}
   */
  @Override
  public JapaneseDate date(Era era, int yearOfEra, int month, int dayOfMonth) {
    if (era instanceof JapaneseEra == false) {
      throw new ClassCastException("Era must be JapaneseEra");
    }
    return JapaneseDate.of((JapaneseEra) era, yearOfEra, month, dayOfMonth);
  }

  /**
   * Obtains a local date in Japanese calendar system from the
   * proleptic-year, month-of-year and day-of-month fields.
   * <p>
   * The Japanese proleptic year, month and day-of-month are the same as those
   * in the ISO calendar system. They are not reset when the era changes.
   *
   * @param prolepticYear the proleptic-year
   * @param month the month-of-year
   * @param dayOfMonth the day-of-month
   * @return the Japanese local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override
  public JapaneseDate date(int prolepticYear, int month, int dayOfMonth) {
    return new JapaneseDate(LocalDate.of(prolepticYear, month, dayOfMonth));
  }

  /**
   * Obtains a local date in Japanese calendar system from the
   * era, year-of-era and day-of-year fields.
   * <p>
   * The day-of-year in this factory is expressed relative to the start of the year-of-era.
   * This definition changes the normal meaning of day-of-year only in those years
   * where the year-of-era is reset to one due to a change in the era.
   * For example:
   * <pre>
   *  6th Jan Showa 64 = day-of-year 6
   *  7th Jan Showa 64 = day-of-year 7
   *  8th Jan Heisei 1 = day-of-year 1
   *  9th Jan Heisei 1 = day-of-year 2
   * </pre>
   *
   * @param era the Japanese era, not null
   * @param yearOfEra the year-of-era
   * @param dayOfYear the day-of-year
   * @return the Japanese local date, not null
   * @throws DateTimeException if unable to create the date
   * @throws ClassCastException if the {@code era} is not a {@code JapaneseEra}
   */
  @Override
  public JapaneseDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
    return JapaneseDate.ofYearDay((JapaneseEra) era, yearOfEra, dayOfYear);
  }

  /**
   * Obtains a local date in Japanese calendar system from the
   * proleptic-year and day-of-year fields.
   * <p>
   * The day-of-year in this factory is expressed relative to the start of the proleptic year.
   * The Japanese proleptic year and day-of-year are the same as those in the ISO calendar system.
   * They are not reset when the era changes.
   *
   * @param prolepticYear the proleptic-year
   * @param dayOfYear the day-of-year
   * @return the Japanese local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override
  public JapaneseDate dateYearDay(int prolepticYear, int dayOfYear) {
    return new JapaneseDate(LocalDate.ofYearDay(prolepticYear, dayOfYear));
  }

  /**
   * Obtains a local date in the Japanese calendar system from the epoch-day.
   *
   * @param epochDay the epoch day
   * @return the Japanese local date, not null
   * @throws DateTimeException if unable to create the date
   */
  @Override  // override with covariant return type
  public JapaneseDate dateEpochDay(long epochDay) {
    return new JapaneseDate(LocalDate.ofEpochDay(epochDay));
  }

  @Override
  public JapaneseDate dateNow() {
    return dateNow(Clock.systemDefaultZone());
  }

  @Override
  public JapaneseDate dateNow(ZoneId zone) {
    return dateNow(Clock.system(zone));
  }

  @Override
  public JapaneseDate dateNow(Clock clock) {
    return date(LocalDate.now(clock));
  }

  @Override
  public JapaneseDate date(TemporalAccessor temporal) {
    if (temporal instanceof JapaneseDate) {
      return (JapaneseDate) temporal;
    }
    return new JapaneseDate(LocalDate.from(temporal));
  }

  @Override
  @SuppressWarnings("unchecked")
  public ChronoLocalDateTime<JapaneseDate> localDateTime(TemporalAccessor temporal) {
    return (ChronoLocalDateTime<JapaneseDate>) super.localDateTime(temporal);
  }

  @Override
  @SuppressWarnings("unchecked")
  public ChronoZonedDateTime<JapaneseDate> zonedDateTime(TemporalAccessor temporal) {
    return (ChronoZonedDateTime<JapaneseDate>) super.zonedDateTime(temporal);
  }

  @Override
  @SuppressWarnings("unchecked")
  public ChronoZonedDateTime<JapaneseDate> zonedDateTime(Instant instant, ZoneId zone) {
    return (ChronoZonedDateTime<JapaneseDate>) super.zonedDateTime(instant, zone);
  }

  //-----------------------------------------------------------------------

  /**
   * Checks if the specified year is a leap year.
   * <p>
   * Japanese calendar leap years occur exactly in line with ISO leap years.
   * This method does not validate the year passed in, and only has a
   * well-defined result for years in the supported range.
   *
   * @param prolepticYear the proleptic-year to check, not validated for range
   * @return true if the year is a leap year
   */
  @Override
  public boolean isLeapYear(long prolepticYear) {
    return IsoChronology.INSTANCE.isLeapYear(prolepticYear);
  }

  @Override
  public int prolepticYear(Era era, int yearOfEra) {
    if (era instanceof JapaneseEra == false) {
      throw new ClassCastException("Era must be JapaneseEra");
    }

    JapaneseEra jera = (JapaneseEra) era;
    int gregorianYear = jera.getPrivateEra().getSinceDate().getYear() + yearOfEra - 1;
    if (yearOfEra == 1) {
      return gregorianYear;
    }
    if (gregorianYear >= Year.MIN_VALUE && gregorianYear <= Year.MAX_VALUE) {
      LocalGregorianCalendar.Date jdate = JCAL.newCalendarDate(null);
      jdate.setEra(jera.getPrivateEra()).setDate(yearOfEra, 1, 1);
      if (JapaneseChronology.JCAL.validate(jdate)) {
        return gregorianYear;
      }
    }
    throw new DateTimeException("Invalid yearOfEra value");
  }

  /**
   * Returns the calendar system era object from the given numeric value.
   *
   * See the description of each Era for the numeric values of:
   * {@link JapaneseEra#HEISEI}, {@link JapaneseEra#SHOWA},{@link JapaneseEra#TAISHO},
   * {@link JapaneseEra#MEIJI}), only Meiji and later eras are supported.
   *
   * @param eraValue the era value
   * @return the Japanese {@code Era} for the given numeric era value
   * @throws DateTimeException if {@code eraValue} is invalid
   */
  @Override
  public JapaneseEra eraOf(int eraValue) {
    return JapaneseEra.of(eraValue);
  }

  @Override
  public List<Era> eras() {
    return Arrays.<Era>asList(JapaneseEra.values());
  }

  JapaneseEra getCurrentEra() {
    // Assume that the last JapaneseEra is the current one.
    JapaneseEra[] eras = JapaneseEra.values();
    return eras[eras.length - 1];
  }

  //-----------------------------------------------------------------------
  @Override
  public ValueRange range(ChronoField field) {
    switch (field) {
      case ALIGNED_DAY_OF_WEEK_IN_MONTH:
      case ALIGNED_DAY_OF_WEEK_IN_YEAR:
      case ALIGNED_WEEK_OF_MONTH:
      case ALIGNED_WEEK_OF_YEAR:
        throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
      case YEAR_OF_ERA: {
        Calendar jcal = Calendar.getInstance(LOCALE);
        int startYear = getCurrentEra().getPrivateEra().getSinceDate().getYear();
        return ValueRange.of(1, jcal.getGreatestMinimum(Calendar.YEAR),
            jcal.getLeastMaximum(Calendar.YEAR) + 1, // +1 due to the different definitions
            Year.MAX_VALUE - startYear);
      }
      case DAY_OF_YEAR: {
        Calendar jcal = Calendar.getInstance(LOCALE);
        int fieldIndex = Calendar.DAY_OF_YEAR;
        return ValueRange.of(jcal.getMinimum(fieldIndex), jcal.getGreatestMinimum(fieldIndex),
            jcal.getLeastMaximum(fieldIndex), jcal.getMaximum(fieldIndex));
      }
      case YEAR:
        return ValueRange.of(JapaneseDate.MEIJI_6_ISODATE.getYear(), Year.MAX_VALUE);
      case ERA:
        return ValueRange.of(JapaneseEra.MEIJI.getValue(), getCurrentEra().getValue());
      default:
        return field.range();
    }
  }

  //-----------------------------------------------------------------------
  @Override  // override for return type
  public JapaneseDate resolveDate(Map<TemporalField, Long> fieldValues,
      ResolverStyle resolverStyle) {
    return (JapaneseDate) super.resolveDate(fieldValues, resolverStyle);
  }

  @Override
    // override for special Japanese behavior
  ChronoLocalDate resolveYearOfEra(Map<TemporalField, Long> fieldValues,
      ResolverStyle resolverStyle) {
    // validate era and year-of-era
    Long eraLong = fieldValues.get(ERA);
    JapaneseEra era = null;
    if (eraLong != null) {
      era = eraOf(range(ERA).checkValidIntValue(eraLong, ERA));  // always validated
    }
    Long yoeLong = fieldValues.get(YEAR_OF_ERA);
    int yoe = 0;
    if (yoeLong != null) {
      yoe = range(YEAR_OF_ERA).checkValidIntValue(yoeLong, YEAR_OF_ERA);  // always validated
    }
    // if only year-of-era and no year then invent era unless strict
    if (era == null && yoeLong != null && fieldValues.containsKey(YEAR) == false
        && resolverStyle != ResolverStyle.STRICT) {
      era = JapaneseEra.values()[JapaneseEra.values().length - 1];
    }
    // if both present, then try to create date
    if (yoeLong != null && era != null) {
      if (fieldValues.containsKey(MONTH_OF_YEAR)) {
        if (fieldValues.containsKey(DAY_OF_MONTH)) {
          return resolveYMD(era, yoe, fieldValues, resolverStyle);
        }
      }
      if (fieldValues.containsKey(DAY_OF_YEAR)) {
        return resolveYD(era, yoe, fieldValues, resolverStyle);
      }
    }
    return null;
  }

  private int prolepticYearLenient(JapaneseEra era, int yearOfEra) {
    return era.getPrivateEra().getSinceDate().getYear() + yearOfEra - 1;
  }

  private ChronoLocalDate resolveYMD(JapaneseEra era, int yoe, Map<TemporalField, Long> fieldValues,
      ResolverStyle resolverStyle) {
    fieldValues.remove(ERA);
    fieldValues.remove(YEAR_OF_ERA);
    if (resolverStyle == ResolverStyle.LENIENT) {
      int y = prolepticYearLenient(era, yoe);
      long months = Math.subtractExact(fieldValues.remove(MONTH_OF_YEAR), 1);
      long days = Math.subtractExact(fieldValues.remove(DAY_OF_MONTH), 1);
      return date(y, 1, 1).plus(months, MONTHS).plus(days, DAYS);
    }
    int moy = range(MONTH_OF_YEAR)
        .checkValidIntValue(fieldValues.remove(MONTH_OF_YEAR), MONTH_OF_YEAR);
    int dom = range(DAY_OF_MONTH)
        .checkValidIntValue(fieldValues.remove(DAY_OF_MONTH), DAY_OF_MONTH);
    if (resolverStyle == ResolverStyle.SMART) {  // previous valid
      if (yoe < 1) {
        throw new DateTimeException("Invalid YearOfEra: " + yoe);
      }
      int y = prolepticYearLenient(era, yoe);
      JapaneseDate result;
      try {
        result = date(y, moy, dom);
      } catch (DateTimeException ex) {
        result = date(y, moy, 1).with(TemporalAdjusters.lastDayOfMonth());
      }
      // handle the era being changed
      // only allow if the new date is in the same Jan-Dec as the era change
      // determine by ensuring either original yoe or result yoe is 1
      if (result.getEra() != era && result.get(YEAR_OF_ERA) > 1 && yoe > 1) {
        throw new DateTimeException("Invalid YearOfEra for Era: " + era + " " + yoe);
      }
      return result;
    }
    return date(era, yoe, moy, dom);
  }

  private ChronoLocalDate resolveYD(JapaneseEra era, int yoe, Map<TemporalField, Long> fieldValues,
      ResolverStyle resolverStyle) {
    fieldValues.remove(ERA);
    fieldValues.remove(YEAR_OF_ERA);
    if (resolverStyle == ResolverStyle.LENIENT) {
      int y = prolepticYearLenient(era, yoe);
      long days = Math.subtractExact(fieldValues.remove(DAY_OF_YEAR), 1);
      return dateYearDay(y, 1).plus(days, DAYS);
    }
    int doy = range(DAY_OF_YEAR).checkValidIntValue(fieldValues.remove(DAY_OF_YEAR), DAY_OF_YEAR);
    return dateYearDay(era, yoe, doy);  // smart is same as strict
  }

  //-----------------------------------------------------------------------

  /**
   * Writes the Chronology using a
   * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
   *
   * @return the instance of {@code Ser}, not null
   * @serialData <pre>
   *  out.writeByte(1);     // identifies a Chronology
   *  out.writeUTF(getId());
   * </pre>
   */
  @Override
  Object writeReplace() {
    return super.writeReplace();
  }

  /**
   * Defend against malicious streams.
   *
   * @param s the stream to read
   * @throws InvalidObjectException always
   */
  private void readObject(ObjectInputStream s) throws InvalidObjectException {
    throw new InvalidObjectException("Deserialization via serialization delegate");
  }
}
